net-mgmt/rubygem-oxidized-web: update to support puma6

The recent update from rubygem-puma5 to rubygem-puma6 broke
rubygem-oxidized-web. This patch fixes it (+ has been submitted upstream).

PR: 272441
(cherry picked from commit c8b47f91bca080d5a8212a8608f1b36d99de1893)